yeah no one will forget that one
cuz no one knows that one you`re funny alleidante
dont even know whats that parody you dumb A

Well, The whole episode (ep100) takes parody of the nintendo wii, dating sims, tetris, and most of all nintendo's Dragon Quest RPG game. It also takes the mic out of a basic game structure, and character stereotypes of that genre.
And, lastly Gintama twists these stereotypes into its own way, to appeal to its audience, and of course, make them laugh! :D